The present invention relates to methods of making microelectronic assemblies, such as semiconductor chip packages, including an electrically and/or thermally conductive element.
Modern electronic devices utilize semiconductor chips, commonly referred to as “integrated circuits”, which incorporate numerous electronic elements. These chips are mounted on substrates that physically support the chips and electrically interconnect each chip with other elements of a circuit. The substrate may be a part of a chip package including terminals for interconnecting the chip with external circuit elements. The interconnection between the chip and its supporting substrate is commonly referred to as a “first level” interconnection. The interconnection between the substrate and the larger elements of the circuit is commonly referred to as a “second level” interconnection.
A plurality of semiconductor chips may be assembled with a substantially continuous strip, as disclosed in certain embodiments of WO 94/03036, the disclosure of which is hereby incorporated by reference herein. The strip may have a plurality of sprocket holes for advancing the strip in a direction for assembly with semiconductor chips. The strip has leads connected to terminals on a surface of the strip that faces away from the chips. The strip includes apertures aligned with the leads. The strip is disposed on top of the chips so that the leads generally extend over the contacts of the chips. A bonding tool is utilized to bond each lead to a contact, by advancing the tool toward a lead and forcing the lead toward the contact on the chip. Heat and/or ultrasonic vibration is applied to the lead by the tool so as to bond the lead to the contact. Alternatively, a wafer incorporating a plurality of chips is assembled with a sheet incorporating a plurality of interposers. The wafer and sheet are severed to provide individual packages.
After forming semiconductor chip packages, the individual packages may be assembled with an electrically or thermally conductive element. A thermal or electrical connection is formed between the element and external circuit elements for shielding or heat spreading. Assembling such individual elements, commonly known as “cans”, with each semiconductor chip is costly and time-consuming.
Despite the foregoing improvements, further advancement in making microelectronic assemblies is desirable.